Machines for drying sheets of paper or like material

ABSTRACT

A high speed drying machine for sheets of paper coated with varnish or the like in which the sheets pass on a perforated conveyor firstly between an upper chamber from which high temperature air at high velocity is discharged through apertures onto the conveyor and a lower from which air is withdrawn to create a vacuum which retains the sheet on the conveyor and secondly through similar chambers to which cold air is supplied.

United States Patent Loveday et al.

[15] 3,685,167 1 1 Aug. 22, 1972 [541 MACHINES FOR DRYING SHEETS OF PAPER OR LIKE MATERIAL [72] Inventors: Harry W. Loveday, Blackburn; Jack D. Whittaker, St. Annes on Sea, both of England [73] Assignee: Greenbank Engineering Company Limited, Blackburn, England [22] Filed: July 20, 1970 [21] Appl. No.: 56,409

[30] Foreign Application Priority Data July 29, 1969 Great Britain .....37982/69 [52] US. Cl. ..3 4/66, 34/155, 34/162 {51 l Int. Cl ..F26b 1 9/00 [58] Field of Search", ....34/66, 155, 162

[56] References Cited UNITED STATES PATENTS I 2,838,420 Valente ..'..34/162 3,096,161 7/ 1963 Morrison et al. ..34/162 3,319,353 5/1967 Matsunami et al. ..34/l62 2,671,969 3/1954 Mayer ..34/66 2,958,379 1 H1960 Hornbostel ..162/306 X 3,359,648 12/1967 Overly et al. ..34/l62 X 3,447,247 6/l969 Daane ..34/l55 X Primary E.raminer-Carroll B. Dority. Jr. Attorney-Norris & Bateman 5 7 ABSTRACT A high speed drying machine for sheets of paper coated with varnish or the like in which the sheets .pass on a perforated conveyor firstly between an upper chamber from which high temperature air at high velocity is discharged through apertures onto the conveyor and a lower from which airis withdrawn to create a vacuum which retains the sheet on the conveyor and secondly through similar chambers to which cold air is supplied.

8 Clains, 4 Drawing Figures PATENTED 1822 I912 3585.167

SHEET 1 BF 2 HARRY WINSTON LOVEDAY JACK DEARDEN WHITTAKER ArmQ/VEVS MACHINES FOR DRYING SHEETS OF PAPER OR LIKE MATERIAL This invention relates to improvements in machines for drying sheets and more particularly to drying sheets of paper coated with varnish or the like.

The object of the invention is to provide means for transferring sheets particularly of paper at predetermined intervals from a varnishing or lacquering head through a drying machine at high speeds of 300 to 500 feet per minute and at high temperatures of a maximum of550-600 F.

According to the invention a drying machine comprises a perforated conveyor to receive the sheet material between an upper chamber to which high pressure air is supplied and a lower chamber forming a vacuum chamber, the air passing through the-conveyor and the suction on the underside thereof maintaining the sheet in contact therewith.

The invention will be described with reference to the accompanying drawings:

FIG. 1 is a diagrammatic longitudinal sectionv through the drying machine;

FlG. 2 is a diagrammatic transverse section on line 2-2 FIG. 1; a

FIG. 3 is an enlarged detail longitudinal section;

FIG. 4 is a detail longitudinal section showing a modified form of jets.

The machine comprises an upper chamber 1 to which heated air is supplied by a fan 2 and a lower chamber 3 to which a vacuum is applied, and a conveyor 4 for the sheets travelling through the machine between the two chambers, the fan 2 drawing air from the lower chamber 3 to create a vacuum therein. The top 12 of chamber 3 is perforated at The upper chamber 1 is supplied with high temperature air at a temperature of 550 to 600 F to dry the chamber 5 supplied with cool air to cool the sheets.

The conveyor 4 is constructed of perforated slats or trays 5a to allow for the passage of the air and for the vacuum or suction on the underside to hold the sheets 6 in contact with the slats or trays.

Difficulty has been experienced in drying thin paper sheets as the pattern of the perforations in the slats or trays 5a was reproduced on the backs-of the sheets and to overcome this defect the slats or trays forming the conveyor are covered by an endless blanket or overlay 70f a pervious fire resistant material such as that sold under the name of TEKLAN.

The blanket or overlay 7 is carried on the steel slat conveyor 4 whose upper surfaces are finely perforated with holes 10 to a free area 9 and carried by means of side chains 11 of the conveyor. The conveyor chains 11 slide on rails and are of a section designed to seal the sides of the conveyor.

The permeable fireproof blanket or overlay 7 is essential for the transporting of lightweight sheets or label paper while equally it will carry heavy lacquer boards. The blanket or overlay 7 is not so essential when conveying lacquer boards and the heavier types of sheet may be carried directly on the perforated conveyor 4.

The high temperature high velocity air is projected through apertures 13 (FIG. 3) or nozzles 14 (FIG. 4) in the bottom wall 8 of chamber 1 onto the conveyed sheet 6 and all drying medium is drawn through the permeable blanket or overlay 7, through apertures 10 in the conveyor trays 4 under the action of the fan unit 2. The fan unit 2 produces a negative or vacuum influencein the lower compartment beneath the conveyor and holds the sheet 6on the blanket or overlay 7. On discharge from the fan 2 a portion of the drying medium is ejected to atmosphere through a duct 15 while a portion is'recirculated, through a duct 16, reheated by a heater l7 and fed into a second fan unit 18 to complete the recirculation circuit.

The same operation is followed in the cooling zone 5 with the exception that all cooling air having been induced through the fabric by a fan unit 19 and into a vacuum compartment 21 is ejected to atmosphere through a duct 22 and all cooling air is taken direct from atmosphere through a duct 23 and no recirculation in this area takes place.

The air may pass through perforations 13 in the base of the chamber or through jets 14 (FIG. 4) preferably arranged in rows the rows being arranged to alternately direct the air forwardly and rearwardly of the direction of travel of the conveyor 4.

An air jet 24 may be provided at the end of the conveyor to lift the leading edge of the sheet from the conveyor for transfer therefron, the conveyor 4 travelling" back under the lower chambers 21, 3.

What I claim is:

l. A machine for drying sheets of paper coated with varnish or the like the invention comprising a perforated endless conveyor to-receive the sheet material, an upper chamber to which high pressure air is supplied, a perforated bottom for said upper chamber, and a lower chamber forming a vacuum chamber, a perforated top for said vacuum chamber between which chambers the conveyor passes, the air passing from the upper chamber and through the conveyor to the lower chamber, the vacuum therein maintaining the sheet in contact with the surface of the conveyor, and said conveyor comprising perforated trays and endless chains on which the trays are mounted and which form a seal for the sides of the trays.

2. The machine defined in claim 1, wherein said conveyor has a generally horizontally moving air pervious upper flight, and longitudinally spaced hot air and cool air drying means disposed along said flight to act in succession on said sheets, said hot air drying means comprising means supplying high pressure hot air to said upper chamber, and said cool air drying means being located to receive said sheets after they have been subjected to hot air drying and comprising means defining a high pressure cool air chamber above the flight and discharging cool air toward the flight and means defining a reduced pressure cool air chamber below the flight adapted to receive cool drying air after passage through the flight and direct it toward an exhaust.

3. A machine for drying sheets of paper as in claim 2 in which a blanket or overlay of porous fireproof material covers the conveyor flight.

4. The machine defined in claim 2, wherein means is provided whereby some of the hot drying air from said vacuum chamber is reheated and recirculated into said upper hot air chamber.

5. The machine defined in claim 2, wherein a blower fan assembly is provided in the hot air drying means 7. The machine defined in claim 6 wherein said cooling air is substantially at ambient temperature.

8. A machine for drying sheets of paper as in claim 2 having an air jet at the cool drying air end of the conveyor to lift the leading end of the sheet therefrom. 

1. A machine for drying sheets of paper coated with varnish or the like the invention comprising a perforated endless conveyor to receive the sheet material, an upper chamber to which high pressure air is supplied, a perforated bottom for said upper chamber, and a lower chamber forming a vacuum chamber, a perforated top for said vacuum chamber between which chambers the conveyor passes, the air passing from the upper chamber and through the conveyor to the lower chamber, the vacuum therein maintaining the sheet in contact with the surface of the conveyor, and said conveyor comprising perforated trays and endless chains on which the trays are mounted and which form a seal for the sides of the trays.
 2. The machine defined in claim 1, wherein said conveyor has a generally horizontally moving air pervious upper flight, and longitudinally spaced hot air and cool air drying means disposed along said flight to act in succession on said sheets, said hot air drying means comprising means supplying high pressure hot air to said upper chamber, and said cool air drying means being located to receive said sheets after they have been subjected to hot air drying and comprising means defining a high pressure cool air chamber above the flight and discharging cool air toward the flight and means defining a reduced pressure cool air chamber below the flight adapted to receive cool drying air after passage through the flight and direct it toward an exhaust.
 3. A machine for drying sheets of paper as in claim 2 in which a blanket or overlay of porous fireproof material covers the conveyor flight.
 4. The machine defined in claim 2, wherein means is provided whereby some of the hot drying air from said vacuum chamber is reheated and recirculated into said upper hot air chamber.
 5. The machine defined in claim 2, wherein a blower fan assembly is provided in the hot air drying means with its intake connected to receive some of the still warm drying air from said lower chamber and its outlet connected to discharge air back into said upper chamber.
 6. The machine defined in claim 2, wherein said conveyor flight is driven at a speed of about 300-500 feet per minute, and said air in the upper chamber of the hot air drying means has a temperature of about 550* to 600* F.
 7. The machine defined in claim 6 wherein said cooling air is substantially at ambient temperature.
 8. A machine for drying sheets of paper as in claim 2 having an air jet at the cool drying air end of the conveyor to lift the leading end of the sheet therefrom. 